This invention relates to a rotating-brush washing apparatus which is particularly useful for washing airplanes, constructed so that a brush part of the apparatus swings or tilts in accordance with the shape of the surface being washed.
FIGS. 1 and 2 of the accompanying drawings show the prior art type of washing apparatus which is in common use for washing airplanes, etc. This apparatus includes a base 1' adapted to be moved up and down by a scissors mechanism 1" on a wheeled platform, and a bed 2' supported on the base 1' via a shaft 3' so that it is capable of a rolling movement from side to side. Two swing arms 4', one on each side, are swingably supported by a shaft 8' on the bed 2'. On the front ends of the arms 4' is supported a shaft 6', on which a roll-shaped rotatable brush 5' is mounted.
On the base or rearward ends of swing arms 4' is mounted a balance weight 7' for balancing the weight of the brush 5', shaft 6', etc. which are mounted on the front ends of the arms 4'. The rotation of a motor 18' mounted on one arm 4' is transmitted via a belt and pulley arrangement to the shaft 6' so that the brush 5' rotates during a washing operation.
Thus, when washing an inclined surface such as the underside of the wings of an airplane (in FIGS. 1 and 2, a wing is indicated by the letter A and an engine is indicated by the letter B), which incline from where the wings are attached to the fuselage toward the tips of the wings, the bed 2' rotates around the shaft 3' and the washing is performed with the surface of brush 5' following along the inclined surface. Also, when washing a surface which inclines in a direction at a right angle to the axis of brush 5' (as illustrated in FIG. 1), the arms 4' swing on the shaft 8' in accordance with the inclination of the surface.
With such a conventional apparatus, there is the drawback that, because the balance weight is necessary, the total weight of the apparatus is increased, thus necessitating larger structural members and larger power systems for the apparatus.
In addition, as shown in FIG. 3, if the swing torque T of arms 4' is constant, the pressing force F of the brush on the surface being washed will vary in accordance with the change in the angle of inclination of the swing arms. In order to minimize the fluctuation of the pressing force F, it is preferable for the inclination angle to be zero, as shown by the following equation: ##EQU1## where R is the distance between the shafts 6' and 8', .theta. is the initial inclination angle of the arms 4', and .alpha. is the angle of swing. The angle .alpha. is the angle of pivotal movement of the arms 4 required by the changing angle of the surface being washed. However, because the balance weight 7' and any other balance mechanism protrude upward, it is difficult for the inclination angle to be made zero. Thus, in this case, in order for the pressing force F to be constant, the swing torque T to be applied to the swing arms must be varied, and for this function a control device would be required.
It is a general object of this invention to provide a rotating-brush washing apparatus which avoids the above drawbacks.